The present invention pertains to an apparatus for removing flammable gas, which is generated by some reaction, especially hydrogen or oxygen.
An apparatus for removing flammable gas is used, as one of the useful examples, in a primary containment vessel (PCV) in an atomic power plant, and removes the flammable gas generated in PCV at the time of an accident. A general type of PCV and an apparatus for removing flammable gas contained in it are explained in reference to figures using the case of a boiling water reactor (BWR) as an example.
FIG. 31 is an outlined systemcross section showing a conventional primary containment vessel. A primary containment vessel (PCV) 102 houses a reactor pressure vessel (RPV) 101, in which a reactor core 107 is built, and comprises of an upper dry well 103 and a lower dry well 104 for enclosing the RPV 101 and a wet well 105 equipped with a suppression pool 105a connected via a vent pipe 106 to the upper dry well 103. And the RPV 101 is enclosed by a biological shield wall 108.
If a primary cooling system pipe of the atomic reactor, such as main vapor pipe 109 connected to the RPV 101, is broken, a high-temperature and high-pressure primary coolant of the atomic reactor is discharged into the upper dry well 103 in PCV 102, rapidly raising the pressure and temperature in the upper dry well 103. The high-temperature and high-pressure coolant discharged into the upper dry well 103 is mixed with a gas in the upper dry well 103, discharged into the water of the suppression pool 105a through the vent pipe 106, and cooled. Most of the thermal energy discharged from the RPV 101 is absorbed in the suppression pool 105a. 
The water of the suppression pool 105a is poured into the RPV 101 by an emergency core cooling system, but the coolant absorbs decay heat from the reactor core in the long term and is discharged to the dry well from an opening in the broken pipe. So, at that time, the pressure and temperature in the upper dry well 103 are always higher than those of the wet well 105. Under such a long-term phenomenon, water, which is a coolant, is decomposed by radiation in a light water reactor of the atomic power plant, generating hydrogen gas and oxygen gas.
Furthermore, when the temperature of a fuel cladding is raised, a reaction is caused between the vapor and zirconium of the fuel cladding material (called a Metal-Water reaction), so that hydrogen gas is generated in a short time. The hydrogen gas generated in this manner is discharged into PCV 102 from the opening in the broken pipe, and the concentration of the hydrogen gas in PCV 102 is gradually raised. Also, since the hydrogen gas is noncondensable, the pressure in PCV 102 is also raised.
When a certain effective countermeasure to such a state cannot be taken and the concentration of the hydrogen gas and that of the oxygen gas are raised to 4 vol % and 5 vol % , respectively, that is, when the concentration of the flammable gas exceeds a certain flammability limit, the gases reach the flammable state. If the concentration of the hydrogen gas is further raised, there is a possibility that an explosive reaction will occur.
As an effective countermeasure to such a situation, in a conventional nuclear power plant of BWR, the inside of PCV is strictly prevented from becoming a flammable atmosphere due to a large amount of hydrogen gas generated in a short time by the Metal-Water reaction, by means of substituting the inside of PCV by nitrogen gas, so that the concentration of the oxygen gas is kept at a low level and therefore a special safety level is achieved.
Also, the gas in PCV is absorbed to the outside of PCV by a flammable gas concentration controller installed outside PCV to remove the hydrogen gas; it has a recombining apparatus and a blower, with the hydrogen gas and oxygen gas being recycled to water by recombination occurring by raising the temperature. The residual gas is cooled and recycled to PCV, so that an increase in the concentration of the flammable gas is suppressed.
Also, as a method that statically controls the flammable gas concentration without the above-mentioned external power source, a method that arranges several catalytic recombining apparatuses for promoting a recombination reaction using an oxidizing catalyst of hydrogen set in PCV has been developed. The constitution of such an apparatus for removing a flammable gas is described in U.S. Pat. Nos. 5,301,217, 5,473,646, 5,167,908, for instance.
FIG. 32 is an oblique view showing an outline of the conventional catalytic recombining apparatus 110 installed in PCV 102. A case 112 for housing an oxidizing catalyst of hydrogen 111 is equipped with two openings 113a and 113b that are always opened. Also, the gas in PCV is introduced into a catalyst layer from the opening 113b installed at the lower side of the case 112. If the concentration of the flammable gas in PCV is raised, the recombination reaction of hydrogen and oxygen is caused in the case 112 by the catalyst 111. The gas is warmed by the heat of the reaction and discharged from the opening 113a at the upper side of the case 112. A naturally circulating flow passing through the catalytic, recombining apparatus is then formed by the heat by the reaction due to the catalyst 111.
Compared with the conventional flammable gas concentration control system that absorbs the gas in PCV to the outside of PCV and recycles the hydrogen gas and the oxygen gas to water due to its recombination by raising the temperature, the above-mentioned catalytic recombining apparatus is economically excellent, and easily repaired without special operations at the time of an accident. However, the catalyst housed in the catalytic recombining apparatus may be poisoned by a substance represented by an iodine compound present in PCV at the time of an accident, so that there is a possibility that the performance of removing flammable gas is lowered.
In order to prevent the decrease in the catalyst function due to the catalyst poison, a method that separates the catalyst from the gas atmosphere in usual condition, releases the separation of the catalyst using the increase of the temperature in PCV as a trigger, and removes the catalyst poison by interposing a filter before passing a gas through the catalyst, is proposed. However, although the filter proposed by this method is suitable for the removal of grease particles or aerosol particles, it is not suitable for the removal of gaseous iodine, which has a large catalyst poison effect.
Also, when the temperature in PCV is used as a trigger for the release of the catalyst separation, there is a great possibility that the separation will be released although the oxygen concentration in PCV is still low at the initial stage of an accident, so it is not optimum as a timing of the separation release.
When the flammable gas concentration control system or the apparatus for removing flammable gas is not operated, several tens of hours pass until the atmosphere in PCV reaches a flammability limit at the time of an accident. In other words, even if the apparatus for removing a flammable gas is not operated for several tens of hours, it does not reach the flammability limit. So, separating the catalyst from the gas atmosphere during such a period is an effective way to prevent the decrease of the function of the catalyst.
However, in the above-mentioned catalytic recombining apparatus in which the openings are always opened, or in the above-mentioned catalytic recombining apparatus in which the temperature in PCV is used as a trigger to release the catalyst separation, the time exposed to a high-concentration catalyst poison present in the initial stage of the accident occurrence is so long that the function of the catalyst decreases. As a result, it can also be considered that the catalyst does not function sufficiently for the case wherein the promotion of the recombination reaction is much expected.
The present invention considered the above-mentioned problems, and its objective is to separate the catalyst from the atmosphere in the housing vessel when the action of the catalyst is not required, to prevent the decrease of the function of the catalyst due to the catalyst poison, to appropriately release the separation of the catalyst in accordance with the concentration of the flammable gas, and to maintain the concentration of the flammable gas at the flammability limit or less over a long term.
Furthermore, its purpose is to raise the activation of the catalyst by preheating the catalyst surface, to suppress poisoning of the catalyst poison, and to save the cost of the apparatus with the catalyst.
In order to achieve the above-mentioned objectives, the present invention provides an apparatus for removing a flammable gas, by using catalytic recombination means, comprising:
a catalyst for reacting the flammable gas;
a first case that houses the catalyst with at least one opening;
at least one first lid mounted to the first case to cover the opening in a usual state and to uncover the opening in an emergency state,
each first lid having a first lid attachment mechanism mounted to the opening of the first case and arranged to set the first lid to a closed state under the normal conditions,
each first lid having a first lid detachment mechanism arranged to set the first lid to an open state by operating the lid attachment mechanism in response to the increase in the concentration of the flammable gas in the atmosphere in the vicinity of the outside of the first case.
With such a constitution, when the concentration of hydrogen and oxygen in PCV is low, the opening of the case of the apparatus is covered with the first lid, so that the degradation of the catalyst can be prevented. Also, if the concentration of hydrogen and oxygen increases, the first lid is opened and the apparatus is started, so that the atmosphere in PCV can be maintained to less than the flammability limit.
Moreover, the first lid attachment mechanism may comprise an adhesive part that adheres the first lid and the first case and is melted as soon as the temperature reaches above predetermined level, and the first lid detachment mechanism may comprise an oxidizing catalyst of hydrogen at least partially in contact with the adhesive part.
Thus, if the concentration of hydrogen and oxygen increases, since the catalyst installed at the first lid generates heat and weakens the action of the adhesive part, the first lid can be easily and reliably opened.
Moreover, the first lid attachment mechanism may comprise a magnetic material arranged at least partially on the opening of the first case, and the first lid detachment mechanism may comprises a vessel for housing a substance for generating a noncondensable gas in response to the increase in the temperature, which is installed in the vicinity of the inner wall surface of the first case; and the first lid is opened by transferring the noncondensable gas, which is generated in response to the increase in the temperature of the substance for generating the noncondensable gas, into the first case.
With such a constitution, if the substance for generating the noncondensable gas is heated, the noncondensable gas is discharged into the first case, so that the internal pressure of the first case is raised. Thereby, the first lid installed at the opening is opened, and as a result, the catalyst is activated. So the degradation of the catalyst due to the catalyst poison prior to the activation can be prevented.
Also, at this situation, it is appropriate that the oxidizing catalyst of hydrogen is arranged in the vicinity of the vessel for housing the substance for generating the noncondensable gas or at the outer wall of the case or its vicinity. Thus, only when the concentration of hydrogen and oxygen outside the first case increases, the temperature of the substance for generating the noncondensable gas is raised by the heat generated by a catalytic reaction or hydrogen occlusion reaction, and the noncondensable gas is discharged, so that the internal pressure of the first case is raised and thereby the first lid is opened and the catalyst is activated. For this reason, only when the concentration of hydrogen and oxygen reaches the degree that requires the catalyst is the apparatus started, so that the functional decrease of the catalyst due to the catalyst poison prior to starting can be prevented.
Instead of the oxidizing hydrogen catalyst, a hydrogen occlusion alloy may also be arranged. In this case, the hydrogen occlusion alloy is arranged so that it communicates with the external space of the first case via a filter. Thus, if the concentration of hydrogen in the external atmosphere of the first case increases, the hydrogen occlusion alloy absorbs the hydrogen and generates heat, which raises the temperature of the vessel for housing the substance for generating the noncondensable gas, so that the noncondensable gas is discharged into the case through the filter, thereby increasing the internal pressure of the first case.
Thereby, the first lid is opened and the catalyst is activated, so the atmosphere in PCV can be maintained at less than the flammability limit. Also, in this case, since the first lid of the case is opened after detecting the increase in the concentration of hydrogen outside of the first case, the catalyst can be prevented from being unnecessarily exposed to the catalyst poison.
Moreover, the first lid attachment mechanism may comprise an adhesive part that adheres the first lid and the first case and is melted as soon as the temperature reaches above a predetermined level, and the first lid detachment mechanism may comprise a heating element installed at least partially at the first lid in contact with the adhesive part. And it is preferable to set a flammable gas sensor installed outside of the first case that sends a current in response to the increase in the concentration in the flammable gas, and an electroconductive substance for connecting the heating element and the flammable gas sensor.
With such a constitution, when the concentration of the flammable gas in PCV exceeds a prescribed concentration, a prescribed current flows to the electroconductive means from the flammable gas sensor and the adhesive part is melted by raising the temperature of the heating element, so that the lid is opened, thereby activating the catalyst. As a result, when the concentration of the flammable gas of the atmosphere in PCV is under the concentration that requires the catalyst, the catalyst is separated from the gas atmosphere, so that the degradation due to the catalyst poison can be prevented.
Moreover, the first lid attachment mechanism may comprise a lid support means installed in connection with the first lid and supports the first lid from the inside of the first case, and the first lid detachment mechanism may comprise a flammable gas sensor installed outside of the first case that sends a current in response to the increase in the concentration of the flammable gas. And it is preferable to set a vessel for housing a substance for generating a noncondensable gas in response to the increase in the temperature, which is installed inside the first case, and a heating element installed in contact with the vessel for housing the substance for generating the noncondensable gas, and an electroconductive substance for connecting the heating element and the flammable gas sensor, and a pressure driving means for driving the first lid support means in response to the increase in the internal pressure of the vessel for housing the substance for generating the noncondensable gas, driven by the generation of the noncondensable gas so that the first lid attachment mechanism is operated, thereby opening the first lid.
With such a constitution, particularly when a metal hydride is used as the substance for generating the noncondensable gas, when the concentration of the flammable gas of the atmosphere outside the first case increases up to a first prescribed concentration, the temperature of the heating element is raised in accordance with the current output from the flammable gas sensor, and the hydrogen is discharged by heating the metal hydride.
The first lid is opened by the pressure driving means being driven by the pressure due to the hydrogen discharge from the metal hydride, so that the catalyst is activated. Also, if the concentration of the flammable gas of the atmosphere outside the first case decreases to a second prescribed concentration, the hydrogen is absorbed into the metal hydride by a reverse process so that the first lid installed at the opening of the case is closed. In this way, the degradation due to the catalyst poison of the catalyst housed in the case can be suppressed.
Moreover, the first lid attachment mechanism may comprise a wire whose one end is connected to the side surface of the first case and the other end is connected to the first lid, and which closes the first lid by a certain tension level under the usual state, and the first lid detachment mechanism may comprise a wire cutter installed halfway at the wire that cuts the wire in response to the increase in the concentration of the flammable gas.
With such a constitution, the wire is cut at a preset temperature, so that the lid can be opened.
In this case, it is preferable to set an auxiliary wire installed in a branched state and a dashpot for supporting one end of the auxiliary wire. With the action of the dashpot, a time delay is given until the first lid installed at the opening of the first case is fully opened, so that the exposure time of the catalyst to the atmosphere outside the first case is delayed. Thereby, the functional decrease of the catalyst due to the catalyst poison can be suppressed.
Instead of the wire cutter mentioned above, it is also preferable to set a wire cutting means, equipped with a heating element installed at an expected cut part of the wire and is melted as soon as the temperature reaches a predetermined level, and a heating means for increasing the temperature of the heating element in response to the increase in the concentration of the surrounding flammable gas.
For example, when an oxidizing hydrogen catalyst is used as the heating means, heat of reaction is generated along with the increase in the concentration of hydrogen, and the temperature of the expected cut part of the wire is increased, so that the heating element is melted, thereby being able to reliably cut the wire.
Furthermore, the heating means may be equipped with a power source, and an electroconductive circuit composed of an electroconductive substance for connecting the power source and the heating element, and a circuit switch installed in the middle of the electroconductive circuit. In this case, the circuit switch is equipped with a vessel for housing a hydrogen occlusion alloy, which includes a hydrogen inclusion alloy, and is set to the ON state as the volume of the hydrogen occlusion alloy increases with the increase in response to the increase in the concentration of the surrounding hydrogen gas surrounding the hydrogen occlusion alloy. It connects the circuit of the flammable gas sensor utilizing a volume expansion by the hydrogen absorption of the hydrogen occlusion alloy.
Thus, the consumption of the power source of the gas sensor under normal standby conditions and erroneous operation of the flammable gas sensor at the time of regular inspection are suppressed. At the same time, at the time of an accident, the increase in the concentration of hydrogen is detected and the circuit of the gas sensor can be automatically connected.
Furthermore, the apparatus for removing a flammable gas may further comprise a second case that houses the catalyst with at least one opening and is contiguous to the first case. And the first lid detachment mechanism is arranged to set to the first lid to an open state by operating the first lid attachment mechanism in response to the increase in the concentration of the atmosphere in the second case.
With such a constitution, after starting of the catalyst in the second case, the first lid of the first case is opened after a delay-time lapse required in the opening operation of the first lid detachment mechanism by a catalytic heat of reaction generated in the first case of the apparatus. Thus, even after the function of the catalyst in the second case is lowered by the action of the catalyst poison, the catalyst in the first case is started, so that the atmosphere in PCV can be maintained at less than the flammability limit.
Also, the apparatus using catalytic recombining means is not limited to two units; when starting of the catalyst is required over many more steps, the other case that houses the catalyst can also be adjacently arranged. At that time, the catalyst in the other case on standby can be operated in accordance with the degree of influence of the catalyst poison on the second case by respectively changing the transformation temperature of each shape-memory alloy being carried into the each case, so that the reliability as an entire system of the apparatus for removing the flammable gas is improved.
Moreover, it is also preferable to set a shape-memory alloy being carried into the second case, and a connection means for connecting the first lid attachment mechanism and the first lid detachment mechanism. And the first lid detachment mechanism is arranged to set to the first lid to an open state by operating the first lid attachment mechanism in response to the increase in the concentration of the atmosphere in the second case, and the connection means is operated by changing the shape of the shape-memory alloy in response to the temperature in the second case so that the first lid attachment mechanism is operated to set the first lid to be opened.
Thus, several cases house the catalyst can be more easily and reliably started with favorable timing.
Furthermore, it is desirable to have a third case that houses the catalyst with at least one opening, at least one second lid mounted to the third case to cover the opening in a usual state and to uncover the opening in an emergency state, each second lid having a second lid attachment mechanism and a second lid detachment mechanism, shape-memory alloys being carried into the first and second cases, a first connection means for connecting the first lid attachment mechanism and the first lid detachment mechanism, a second connection means for connecting the second lid attachment mechanism and the second lid detachment mechanism.
In this situation, the first lid detachment mechanism are arranged to set to the first lid to an open state by operating the first lid attachment mechanism in response to the increase in the concentration of the atmosphere in the second case, and the second lid detachment mechanism are arranged to set to the second lid to an open state by operating the second lid attachment mechanism in response to the increase in the concentration of the atmosphere in the first case. And the first and second connection means are operated first by changing the shape of the shape-memory alloy in the second case in response to the temperature in the second case so that the first lid attachment mechanism is operated to set the first lid to be opened, and is operated second by changing the shape of the shape-memory alloy in the first case in response to the temperature in the first case so that the second lid attachment mechanism is operated to set the second lid to be opened.
With such a constitution, after starting of the catalyst in the second case, the first lid is opened after the lapse of a delay time required for the temperature increase of the shape-memory alloy device by a catalytic heat of reaction, starting a catalytic reaction. Thereby, even after the function of the catalyst of the second case is lowered by the action of the catalyst poison, the second and third catalytic recombining reactions are sequentially started, so that the atmosphere in PCV can be maintained at less than the flammability limit.
Furthermore, it is also preferable to set a vessel for housing a substance for generating a noncondensable gas in response to the increase in the temperature which is installed in the second case, and a pressure driving means which opens the first lid of the first case by operating the first lid attachment mechanism in response to the increase in the internal pressure of the vessel for housing the substance for generating the noncondensable gas.
With such a constitution, after starting the catalyst in the second case, which is thought that its opening is always opened, the noncondensable gas is discharged by a catalytic heat of reaction, and the pressure inside the cylinder is raised. After a delay time required for the pressure increase, the first lid of the first case is opened, so that a catalytic reaction is started. Thus, even after the function of the catalyst in the second case is lowered by the action of the catalyst poison, the catalyst in the first case is started, so that the atmosphere in PCV can be maintained at less than the flammability limit.
Furthermore, it is also preferable to set the first lid attachment mechanism comprises an adhesive part that adheres the first lid and the first case and is melted as soon as the temperature reaches a predetermined level, and the lid detachment mechanism comprises a heating element installed at least partially at the first lid in contact with the adhesive part, and a flammable gas sensor installed in the second case and sends a current in response to the increase in the concentration of the flammable gas. And an electroconductive substance for connecting the heating element and the heating element and the flammable gas sensor is also arranged.
With such a constitution, after the catalyst in the second case is started, only when the function is lowered and the atmosphere in PCV reaches a preset flammable gas concentration or more, since the first lid of the first case is opened, the functional decrease due to the catalyst poison in the first case can be prevented. Furthermore, the concentration of the flammable gas can be maintained at less than the flammability limit for a long time.
Also, the flammable gas sensor is appropriately installed inside the second case and at the upper part of the catalyst layer.
When the concentration of the flammable gas that passes through the catalyst layer is low and the catalyst functions normally, the concentration of the flammable gas detected by the flammable gas sensor is less than a prescribed concentration, and the first lid of the first case connected to the flammable gas sensor is not opened as normal. On the other hand, if the function of the catalyst positioned at the lower part of the flammable gas sensor is lowered and the concentration of the flammable gas that passes through the catalyst layer is raised and reaches a prescribed concentration, the first lid is opened, so that the reaction is started by a new catalyst that is not exposed to the catalyst poison. Thereby, the concentration of the flammable gas in PCV can be maintained at less than the flammability limit for a long time.
Furthermore, the apparatus for removing the flammable gas may further comprises a vessel operation means for operating the gas sensor housing vessel to be moved in response to the increase in the concentration of the surrounding flammable gas of the gas sensor housing vessel.
The flammable gas sensor appears only when the vessel operation means is operated. Thus, since the flammable gas sensor connected to the first case is exposed to the gas that passes through the catalyst layer after the catalyst in the second case is completely started, the possibility of an early separation release due to erroneous operation can be reduced.
The vessel operation means is equipped with a shape-memory alloy installed in the gas sensor housing vessel. In the means using the shape-memory alloy in the opening of the gas sensor housing vessel, the catalyst layer arranged at the lower side of the flammable gas sensor starts a reaction; if the temperature of the shape-memory alloy is raised by the heat of reaction and reaches the transformation temperature, the vessel is deformed along with the transformation of the shape-memory alloy, so that covering of the flammable gas sensor is removed.
The vessel operation means may also be equipped with a piston connected to the gas sensor housing vessel, a cylinder for housing the piston, and a vessel for housing a substance for generating the noncondensable gas, which is connected to the cylinder and includes the substance for generating the noncondensable gas when the temperature is high. In a method using the noncondensable gas generating substance in the opening of the gas sensor housing vessel, the catalyst layer arranged at the lower side of the flammable gas sensor starts a reaction. If the temperature of the substance is raised by the heat of reaction, the noncondensable gas is generated, so that the internal pressure of the vessel for housing the substance for generating the noncondensable gas is raised, thereby removing the covering of the gas sensor housing vessel.
Also, the apparatus for removing a flammable gas further comprises a heating element selected from the group consisting calcium oxide, sodium oxide, potassium oxide, magnesium oxide, rubidium oxide, strontium oxide, and hydrogen occlusion alloy, which is arranged in contact with the catalyst. If the calcium oxide or sodium oxide is used, since it causes an exothermic reaction with vapor included in the gas exposed to the heating element and generates a hydroxide, the temperature of the catalyst layer is raised, so that the catalyst is activated. Also, if the hydrogen occlusion alloy is used, the catalyst is similarly activated by the heat generation due to a hydrogen absorption reaction. Therefore, the recombination reaction by the catalyst can be further promoted.
Also, the catalyst of the apparatus for removing the flammable gas comprises at least one substance selected from the group consisting of platinum, ruthenium, and palladium; and at least one substance selected from the group of silver, cobalt, manganese, copper and their oxide. The former promotes the oxidation reaction of hydrogen even at normal temperature, but it is generally expensive. Although the latter is inexpensive, the reaction-start temperature is high. With a combination of these, the action of the catalyst is well maintained and the cost can be reduced.
Also, the the lid detachment mechanism may comprise a vessel for housing a substance for generating a noncondensable gas is installed in the vicinity of the inner wall surface of the first case, with the substance for generating the noncondensable gas comprising at least one substance selected from the group consisting of calcium-containing hydrocarbon, sodium-containing hydrocarbon, thallium (I) carbonate, iron (II) carbonate, and a metal hydride. Then the first lid is opened by transferring the noncondensable gas, which is generated in response to the increase in the temperature of the substance for generating the noncondensable gas, into the first case. Along with heating, hydrogen is generated by the metal hydride, with carbon dioxide being generated by the above-mentioned other four kinds of substances.
Also, the catalyst of the apparatus for removing a flammable gas comprises at least one metallic substance unit and its oxide selected from the group consisting platinum, ruthenium, and palladium. Thus, the oxide is reduced by the increase in the hydrogen concentration, and a catalyst composed of the metal unit is newly generated. The removal efficiency of the flammable gas is improved by the catalyst that is newly generated. Also, with the heat generation during the reduction reaction, the temperature of the surface of the catalyst composed of the metal unit is raised, with the activation of the catalyst also being raised. At the same time, poisoning by the catalyst poison can be suppressed.
Also the present invention also provides an apparatus for removing a flammable gas, by using catalytic recombination means, comprising:
a catalyst for reacting the flammable gas;
a case with at least one opening;
a carrier for the catalyst installed in the case, which is a porous columnar body, comprising at least one substance selected from the group consisting of aluminum oxide, silicon oxide, copper, and bronze, whose fine-hole diameter is arranged to set in the range between 1 nm and 1000 nm, with a passage for circulating gas being installed as a cavity in the columnar body.
With such a constitution, instead of a conventional large-scale apparatus for removing a flammable gas, a static flammable gas removal can be realized by a small-scale apparatus with a high efficiency.
Moreover, the columnar body comprises at least one substance selected from the group consisting of platinum, ruthenium, and palladium as the catalyst at a ratio in the range between 1 wt % and 10 wt % . This range is the most appropriate ratio for well maintaining the catalyst performance.
Moreover, the apparatus for removing a flammable gas may further comprise a catalytic support selected from the group consisting active carbon and iron, whose specific surface area is over 500 m2/g, installed by connecting with a columnar body constituting the catalyst, which is molded in a columnar shape in which a passage for gas circulation is installed as a cavity. Iron oxide is generated by the oxygen in the gas before the gas passes through the catalyst body, and the heat generated by the reaction promotes the recombination reaction of hydrogen and oxygen.